If the body fat rate is too high and the weight exceeds 20% of the normal value, it can be regarded as obesity. The body fat rate of athletes can be determined according to sports events. The average of male athletes is 7% ~ 15%, and the average of female athletes is 12%-25%.
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Human muscle ***639. It consists of about 6 billion muscle fibers, the longest is 60 cm, the shortest is only about 1 mm, the big muscle weighs about two kilograms, and the small muscle weighs only a few grams. The average person's muscles account for about 35% to 45% of the body weight.
According to different structures and functions, it can be divided into smooth muscle, myocardial muscle and skeletal muscle, and according to morphology, it can be divided into long muscle, short muscle, platysma muscle and orbicularis oris muscle. Smooth muscle is mainly composed of internal organs and blood vessels, which has the characteristics of slow contraction, long duration and no fatigue. Myocardium constitutes the heart wall, and neither of them contracts with human will, so it is called involuntary muscle. Skeletal muscles are distributed in the head, neck, trunk and limbs, and are usually attached to bones. Skeletal muscle contracts rapidly, forcefully and easily, and can contract and contract with people's will, so it is called voluntary muscle. Skeletal muscle is striated under the microscope, so it is also called striated muscle.
Skeletal muscle is the dynamic part of the exercise system, which is divided into white muscle and red muscle fiber. White muscles contract or stretch rapidly through rapid chemical reactions, while red muscles exercise through continuous oxygen supply. Under the control of the nervous system, skeletal muscles contract and pull bones to produce movement. There are more than 600 human skeletal muscles, which are widely distributed, accounting for about 40% of body weight. Every skeletal muscle, regardless of its size, has a certain shape, structure, position and auxiliary devices, and is rich in blood vessels and lymphatic vessels, which are controlled by certain nerves. Therefore, every skeletal muscle can be regarded as an organ.
References:
Baidu encyclopedia muscle